Process for dyeing articles of polyeth-



PROCESS FOR DYEING ARTICLES OF POLYETH- YLENE TEREPHTHALATE OR CELLULOSE TRI- ACETATE Walter Hees, Koln-Hohenberg, Germany, assignor to Farbenfabriken Bayer Aktiengesellschaft, Leverknsen, Germany, a corporation of Germany Application December 19, 1957 Serial No. 703,738

Claims priority, application Germany January 24, 1957 4 Claims. (Cl. 8-36) No Drawing.

The present invention relates to the dyeing of articles of polyesters or cellulose triacetate; more particularly it concerns a process for dyeing articles of polyesters or cellulose triacetate in an aqueous medium with disperse dyestuifs at boiling temperature. According to the invention this process is carried out in the presence of arylesters of carbonic acid.

As aryl esters of carbonic acid there are particularly suitable the phenyl esters such as diphenyl carbonate and their derivatives substituted in the benzene nucleus, e.g. by alkyl radicals or halogen atoms, such as o-tolyl carbonate, and the mixture of the various cresyl carbonates melting at about 55 C.

Since the aforesaid aryl esters of carbonic acid are generally solid and water-insoluble, provision must be made so that they are present in the dyebath in the dispersed state. For this purpose a solution of the carbonic acid esters in hot alcohol may be added to the dyebath containing a dispersing agent for the esters. Suitable dispersing agents are, for example, the sodium salt of dinaphthylmethane disulfonic acid as well as high molecular weight alkyl sulfates or alkyl sulfonates in the form of their water-soluble sodium or cyclohexylamine salts.

The quantities of aryl esters of carbonic acid required for carrying out the process of the present invention may readily be established by preliminary experiments in each case; quantities of l to grams per litre of the dyebath are generally sufiicient, depending on the desired depth of the dyeing. In general, the aryl esters of carbonic acid having a melting point below 100 C. are to be preferred.

The process according to the invention enables filaments, fibres, foils and other articles of polyesters, for example those of the polyethylene terephthalate class, or of cellulose triacetate, to be dyed in very deep shades with a substantial acceleration of the dyestufi absorption. Compared with the esters of aromatic carboxylic acids and aliphatic or aromatic alcohols such as benzoic Patented Dec. 8, 1959 "ice acid methyl ester, salicylic acid methyl ester or benzoic acid benzyl ester, which have previously been proposed as dyeing accelerators, the aryl esters of carbonic acid exhibit a substantially greater activity. Moreover, they improve in most cases the light fastness of the dyeings.

As disperse dyestuffs, there may be used the dyestuffs known under this designation (cf. for example Diserens, Die neuesten Fortschritte in der Anwendung der Farbstotle, vol. 2, second edition (1949), pages 254-259).

The following examples serve to illustrate the invention without, however, limiting the scope thereof.

Example 1 Polyester fibres of polyethylene terephthalate are dyed at 98 C. in an aqueous bath having a liquor-to-goods ratio of 40:1 and containing per litre 0.75 gram of the disperse dyestulf 1-hydroxy-4-(p-tolyl)-amino-anthraquinone, 4 grams of diphenyl carbonate and 2 grams of the sodium salt of dinaphthylmethane disulfonic acid. The dyeing period is about 2 hours. A deep blue shade of very good light-fastness is thus obtained.

Example 2 Fibres of cellulose triacetate are introduced at a liquor-to-goods ratio of 40:1 into a bath containing per litres 0.75 gram of the disperse dyestufi 1-amino-4-hydroxy-Z-bromo-anthraquinone, 5 grams of diphenyl carbonate and 1 gram of the cyclohexylamine salt of pentadecyl sulfonic acid. The dyeing is carried out in conventional manner at 96-98 C. for 2 hours yielding a deep red shade which is very fast to light.

I claim:

1. A process for dyeing articles made from a member of the group consisting of polyethylene terephthalate and cellulose triacetate which comprises contacting said articles in an aqueous medium at boiling temperature with disperse dyestuffs in the presence of dispersed aryl esters of carbonic acid.

2. A process according to claim 1 wherein diphenyl carbonate is applied as aryl ester of carbonic acid.

3. A process for dyeing an article made from polyethylene terephthalate which comprises contacting said article in an aqueous medium at boiling temperature with a disperse dyestuif in the presence of dispersed diphenyl carbonate.

4. A process for dyeing an article made from cellulose triacetate which comprises contacting said article in an aqueous medium at boiling temperature with a disperse dyestuti in the presence of dispersed diphenyl carbonate.

References Cited in the file of this patent Man Made Textiles for March 1956, pp. 72, 74. 

1. A PROCESS FOR DYEING ARTICLES MADE FROM A MEMBER OF THE GROUP CONSISTING OF POLYETHYLENE TEREPHTHALATE AND CELLULOSE TRIACETATE WHICH COMPRISES CONTACTING SAID AR TICLES IN AN AQUEOUS MEDIUM AT BOILING TEMPERATURE WITH DISPERSE DYESTUFFS IN TH PRESENCE OF DISPERSED ARYL ESTERS OF CARBONIC ACID. 